<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script>
function loadXMLDoc()
{
    var xmlhttp;
    //document.getElementById("myDiv").innerHTML = location.href;
	if (window.XMLHttpRequest)
	{
		//  IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码
		xmlhttp=new XMLHttpRequest();
	}
	else
	{
		// IE6, IE5 浏览器执行代码
		xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
	}
	xmlhttp.onreadystatechange=function()
	{
		if (xmlhttp.readyState==4 && xmlhttp.status==200)
		{
            document.getElementById("myDiv").innerHTML = xmlhttp.responseText;
            /*
                xmlDoc=xmlhttp.responseXML;
                txt="";
                x=xmlDoc.getElementsByTagName("title");
                for (i=0;i<x.length;i++)
                    txt=txt + x[i].childNodes[0].nodeValue + "<br />";
            */
		}
	}
	xmlhttp.open("GET","./text.txt",true);// book.xml
	xmlhttp.send();
}
</script>
</head>
<body>

<div id="myDiv"><h2>使用 AJAX 修改该文本内容</h2></div>
<button type="button" onclick="loadXMLDoc()">修改内容</button>

</body>
</html>